(Negative Selection) Autoreactive. Cells with a T cell receptor that can bind MHC class I or II molecules with at least a weak affinity are chosen by positive selection.
This destroys any T cells that wouldn't function because they couldn't bind MHC (a process known as "death by neglect"). Family loyalty. T-cell lineage commitment in hematopoietic tissue. Multiple selection processes, such as positive selection, negative selection, and agonist selection, that take place during the formation of T cells in the thymus work together to select a functional and self-tolerant T cell repertoire. T cells must be able to recognise the antigen-MHC complex in order to be effective in fighting infections and other foreign cells.
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If a ray-finned fish is to both hover (remain stationary) in the water column and ventilate its gills effectively, then what other structure besides its swim bladder will it use?
A) its pectoral fins
B) its lateral line system
C) its caudal (tail) fin
D) its operculum
If a ray-finned fish is to both hover (remain stationary) in the water column and ventilate its gills effectively, then what other structure besides its swim bladder will it use is D) its operculum.
The operculum is a bony structure that covers and protects the gills of ray-finned fish. It allows for effective ventilation of the gills while the fish hovers in the water column. The swim bladder helps with buoyancy control but does not directly aid in gill ventilation. The pectoral fins and caudal fin aid in movement and maneuverability, but not specifically in hovering or gill ventilation. The lateral line system helps the fish sense changes in water pressure and movement, but is not directly involved in either hovering or gill ventilation.
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A ray-finned fish along with the swim bladder use its operculum to cover and protect its gills. Hence the correct answer is option d.
The operculum is a bony structure that covers and protects the gills of a fish which enables efficient ventilation. When a fish is stationary or hovering, it needs to ventilate its gills to obtain oxygen from the water. The operculum helps to create a constant flow of water over the gills, allowing for efficient gas exchange. It will use its pectoral fins to help maintain a stationary position in the water column, also known as hovering. This along with the swim bladder allows the fish to control its buoyancy and position effectively. The lateral line system, caudal (tail) fin, and other structures play important roles in the fish's movement and navigation but are not primarily used for hovering and ventilating gills.So the correct answer is option d.
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20
Question 6
6. A pea plant with yellow seeds (YY) is crossed with a pea plant with
green seeds (yy)., All seeds from the resulting plants are yellow. Yellow is:
a. dominant
Ob. recessive
c. heterozygous
No answer text provided.
5 pts
< Previous
Answer:
A. dominant
Explanation:
a scientist is examining a fern and wants to find the archegonia, so she looks for a location containing a
A scientist is examining a fern and wants to find the archegonia, so she looks for a location containing a megagametophyte.
The megagametophyte, also known as the embryo sac, is a female gametophyte that is found within the ovule of flowering plants. It is an essential part of the reproductive process and plays a critical role in the development of the plant embryo.
The megagametophyte is formed through a process of meiosis, which produces four haploid cells, three of which eventually degenerate. The remaining cell divides several times to form a multicellular structure that contains several nuclei but no cell walls, known as the embryo sac.
The number and arrangement of these nuclei varies among different plant species.
The megagametophyte is where the egg cell, which is necessary for sexual reproduction, is located. The egg cell is fertilized by a sperm cell that is delivered through the pollen tube, which grows from the male reproductive structure, the pollen grain.
The resulting fertilized egg then develops into the embryo, which eventually becomes the plant embryo.
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Note: complete question:
A scientist is examining a fern and wants to find the archegonia, so she looks for a location containing a
megaphyll.
microgametophyte.
microspore.
stomate.
megagametophyte.
megagametophyte
a difference between a g and an a at a particular nucleotide is an example of a(n) snp. str. microarray. dna transposon. microsatellite.
An illustration of snp is a difference between a g and an a at a specific nucleotide. The correct answer is SNP.
The substitution of a C for a G in the nucleotide sequence AACGAT, which results in the sequence AACCAT, is an illustration of an SNP. The DNA of people might contain numerous SNPs since these varieties happen at a pace of one in each 100-300 nucleotides in the human genome.
A single nucleotide change in a genome is known as an SNP. Likewise, it is a sort of change. Base pair substitution, insertion, deletion, duplication, or variation in DNA is known as a mutation.
The primary distinction between an SNP and a mutation is that a mutation is any change in DNA, from a single to many nucleotide difference, whereas an SNP is a single nucleotide difference in DNA.
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Write a hypothesis about the effect of the red light on the
population. Use the "if.
.then . .. because . . ." format,
and be sure to answer the lesson question: "How does
natural selection change the phenotypes within a
population over time?"
When a phenotype generated by particular alleles helps animals survive and reproduce more than their contemporaries, natural selection may boost the number of the advantageous alleles from a single generation to the next.
Natural selection alters phenotypic in what ways?The effect of natural selection upon single-gene traits can modify allele frequencies and, as a result, phenotypic frequencies. Natural selection on polygenic characteristics can have three effects on phenotypic distributions: directional selection, stabilisation selection, and disruptive selection.
How does the process of natural selection affect population growth over time?Natural selection is an evolutionary mechanism. Organisms that are better adapted to their surroundings are able to prosper and pass on the DNA that helped them thrive. Species change and split as a result of this process.
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herpes simplex virus can only be spread by symptomatic patients. group of answer choices true false
The statement "herpes simplex virus can only be spread by symptomatic patients" is false.
Herpes simplex virus can be spread by both symptomatic and asymptomatic patients. Asymptomatic patients may not show visible symptoms, but they can still transmit the virus to others through viral shedding.
HSV is a highly contagious virus that can be transmitted through direct contact with infected body fluids, such as saliva, genital secretions, or lesions caused by the virus.
The virus can be passed even during times when there are no visible symptoms, which is why it is essential to practice safe sex and take appropriate precautions to prevent the spread of the virus.
It is also important to note that there are two types of herpes simplex virus: HSV-1 and HSV-2. While HSV-1 is typically associated with oral herpes (cold sores) and HSV-2 is associated with genital herpes, both types can infect either location.
Additionally, HSV-1 can be spread to the genitals through oral sex, and HSV-2 can be spread to the mouth through genital-to-oral contact.
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a record of the potential differences generated by the heart and conducted via body fluids to the surface, where it is detected by electrodes, is called a(n) recording.
The record of the potential differences generated by the heart and conducted via body fluids to the surface, where it is detected by electrodes, is called an: electrocardiogram (ECG) recording.
An electrocardiogram is a recording of the electrical activity of the heart. Electrodes are placed on the skin to detect the electrical impulses generated by the heart and transmit them to a machine, which records the data as a graph.
The ECG is a useful tool for diagnosing various heart conditions, such as arrhythmias, conduction abnormalities, and ischemia, and is often performed as a part of routine medical checkups, during cardiac procedures, or in emergency situations.
The recorded data can provide valuable information about the heart's structure and function, helping healthcare providers to identify and manage heart-related issues.
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Ch 15
The nurse is admitting the patient to the nursing unit at the hospital. the nurse is concerned that the patient is at risk of deep vein thrombosis because of which of the following risk factors? Select all that apply.
A. Pt's advanced age
B. Pt's admitting diagnosis of cancer
C. Pt's stated drug allergy to aspirin
D. Pt's history of of prior venous thrombosis
E. Pt's low protein diet
The following risk factors for deep vein thrombosis (DVT) are:
A. Pt's advanced age
B. Pt's admitting diagnosis of cancer
D. Pt's history of prior venous thrombosis
Advanced age is a risk factor for DVT because the risk of developing blood clots increases as we age. Admitting diagnosis of cancer also increases the risk of DVT, as cancer cells can release substances that increase the risk of blood clots. A history of prior venous thrombosis is also a significant risk factor for developing DVT again.
Option C, Pt's stated drug allergy to aspirin, is not a risk factor for DVT. In fact, aspirin is often used as a preventative measure for DVT in some patients.
Option E, Pt's low protein diet, is not a significant risk factor for DVT.
Therefore, the correct options are A, B, and D.
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hair on mammals can be used for all but which of the following? group of answer choices camouflage defense sensory functions insulation all of the above
The correct answer is "e) all of the above". Hair on mammals can be used for camouflage, defense, sensory functions, and insulation.
What four purposes do mammals' hair serve?Hair is used by modern mammals to protect, signal, hide, insulate, and detect their immediate environment. Insulation protects against excessive heat as well as serves to conserve heat, as it does for nocturnal desert animals like the camel.
What purposes do animals' hair serve?Many goods use animal hair. Brushes and stringed instrument bows both use horse hair. Hog bristle, ox hair, and Siberian weasel hair are all used.
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Desert plants are characterized by
A. Broad leaves
B. Succulent stems
C. Deciduous leaves
Desert plants are characterized by Succulent stems .
The correct option is B .
Broad leaves are generally not common in desert plants because they lose water through transpiration, which is the process of water loss from plant leaves. Therefore, desert plants have evolved to have small or narrow leaves to minimize water loss. Succulent plants are a good example of this adaptation. Succulents are characterized by their thick, fleshy stems and leaves, which are able to store large amounts of water for long periods of time.
Also, many desert plants have evolved to retain their leaves year-round, instead of shedding them seasonally like many other types of plants. This adaptation helps to conserve water, as shedding leaves is another way of losing water.
Hence , B is the correct option
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3. Haz un gráfico con los datos de la tabla adjunta. Empieza en el año 0 y termina en 2007. Responde:
a. ¿A qué tipo de crecimiento corresponde, lineal o exponencial?
b. ¿Qué bucle de retroalimentación coincide con este crecimiento?
—Enumera algunos factores que hayan contribuido a este aumento progresivo de la población mundial.
The table referred to in the statement is a data table that establishes the number of inhabitants in different years since -300,000 years ago, where there were 500,000 inhabitants on the planet, until the year 2007, where there were 6.5 billion inhabitants.
To create a graph with two data streams,
Draw two perpendicular lines, one vertical and one horizontal, where the point where they intersect is 0.
On the vertical line, place all the amounts of inhabitants shown in the table, starting from the bottom up.
On the horizontal line, place the years starting at 0, which was the point of intersection of the lines.
Then, join the years with the number of inhabitants as shown in the graph attached in the image.
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--The complete question is, Make a graph with the data from the attached table. Start at year 0 and end in 2007. a. What type of growth does it correspond to, linear or exponential?
b. What feedback loop coincides with this growth?
List some factors that have contributed to this progressive increase in the world population.--
Please help with this one
Biological Organization Levels refers to the order in which elements, structures, and systems are organized, from the smallest element to the largest system. 1) Gene. 2) Chromosome. 3) DNA. 4) Nucleu. 5) Cell. 6) Organism. 7) Population.
What are organization levels?
When talking about biological organization levels, we are referring to the hierarchical order of the different structures that compose individuals and the systems in which they are immersed.
It can go from the smallest things, such as subatomic structures, to the most complex systems, such as biomes.
Among the many different biological organization levels, we can mention the molecular level.
In the exposed example, we need to order hierarchically the elements mentioned at the left, for the smallest molecule, to the largest organization.
The smallest element is the gene. So this is the first level.Genes are arranged in chromosomes. So chromosomes are the second level.Chromosomes compose the DNA molecule, which becomes the third level.DNA is located inside the eukaryotic nucleus. So the nucleus is the fourth level. The nucleus is inside the cell, which is the fifth level.Several cells compose an organism. So the organism is at the sixth level. And finally, many organisms are part of a population, the largest system in this example. This is the seventh level.You can learn more about organization levels at
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